JP2007532456A - Silica-based sols and their production and use - Google Patents

Abstract

The present invention provides (a) a cation exchange resin having at least part of the ion exchange capacity in the form of hydrogen, and (b) contacting the ion exchange resin with an aqueous alkali metal silicate solution to produce an aqueous slurry. (c) Stir the aqueous slurry until the pH of the aqueous phase is in the range of 5.0 to 11.5 and / or stir the aqueous slurry to enable particle aggregation or microgel formation corresponding to S values up to 45% Obtaining a pH of the aqueous phase of at least 5.0, (d) adjusting the pH of the aqueous phase to 9.0 or more using one or more materials comprising at least one aluminum compound, and (e) the ion exchange resin. It is related with the manufacturing method of the sol based on the aqueous | water-based silica characterized by isolate | separating from said aqueous phase after a process (c) or a process (d). The present invention also provides S values in the range of 15-25%, molar ratios Si: Al in the range of 20: 1 to 50: 1, molar ratios Si: X in the range of 5: 1 to 17: 1 ( X is an alkali metal), and relates to a silica-based sol comprising silica-based particles having a SiO ₂ content of at least 5% by weight and a specific surface area of at least 300 m ² / g. Furthermore, the present invention provides (i) an aqueous suspension containing cellulose fibers, and (j) one or more dehydration and retention aids containing the silica-based sol of the present invention is added to the suspension. And (k) a paper manufacturing method, characterized in that the resulting suspension is dewatered to obtain a paper sheet or web.

Description

The present invention relates generally to aqueous silica-based sols suitable for use in papermaking. More particularly, the invention relates to silica-based sols, their production and use in papermaking. The present invention provides an improved process for the production of silica-based sols with improved stability and SiO ₂ content as well as improved dewatering performance.

  In the papermaking arts, an aqueous suspension (referred to as a stock) containing cellulosic fibers and optional fillers and additives is fed to a headbox (which discharges the stock to the forming wire). Water is drained from the stock, so that a wet web of paper is formed on the wire and the web is further dewatered and dried in the drying section of the paper machine. Dehydration and retention aids are usually introduced into the stock to promote dehydration and increase the adsorption of fine particles to cellulose fibers so that they are retained by the fibers on the wire.

Silica-based particle sols are widely used as dehydration and retention aids in combination with charged organic polymers. Such additive systems are among the most effective ones currently in use in the paper industry. One parameter that affects the properties and performance of silica-based sols is specific surface area. Stable, high performance silica-based sols usually contain particles having a specific surface area of at least 300 m ² / g. Another parameter is the S value, which indicates the degree of aggregate or microgel formation. A low S value indicates a high degree of aggregation. High surface area and some degree of agglomeration or microgel formation may be advantageous from a performance point of view, but very high surface area and extensive particle aggregation or microgel formation significantly reduce stability of silica-based sols It requires extreme dilution of the sol to provide sexuality and thereby avoid gel formation.

US Pat. No. 5,368,833 discloses a silica sol containing silica particles having a specific surface area in the range of 750 to 1,000 m ² / g that is surface modified with aluminum to a degree of substitution of 2 to 25% of silicon atoms, The sol has an S value in the range of 8-45%. The patent also includes the steps of acidifying the water glass solution to a pH in the range of 1-4, alkalizing the acid sol with a SiO ₂ content in the range of 7-4.5% by weight, and particle growth of the sol. Disclosed is a method for producing a silica sol comprising the steps of enabling a specific surface area in the range of 750 to 1,000 m ² / g and subjecting the sol to aluminum modification.

U.S. Pat. No. 5,603,805 discloses a silica sol having an S value in the range of 15-40% comprising anionic silica particles, said silica particles may optionally be aluminum modified and have a 300-700 m < ² > / g. Has a specific surface area within the range. Step said patent also to acidic pH in the range of 1 to 4 water glass solution, the step of alkalized with SiO ₂ content within the range of this acid sol 7-5 wt%, and pH of 7-9 Disclosed is a method for producing a silica sol comprising alkalinization of the acid sol to a value and particle growth of the sol to a specific surface area in the range of 300-700 m ² / g, followed by optionally aluminum modification.

  International patent application WO 98/56715 discloses a method for preparing an aqueous polysilicate microgel comprising mixing an aqueous solution of an alkali metal silicate with an aqueous phase of a silica-based material having a pH of 11 or less. . This polysilicate microgel is used as a flocculant in pulp and paper production and in combination with at least one cationic or amphoteric polymer for water purification.

  International Patent Application Publication No. WO 00/66492 generates an acid sol by acidifying an aqueous silicate solution to a pH of 1 to 4 and alkalizing the acid sol in a first alkalinization step. Enabling particle growth and / or heat-treating this alkalized sol at a temperature of at least 30 ° C., alkalinizing the resulting sol in a second alkalizing step, and optionally silica-based sol, eg aluminum A process for the production of an aqueous sol comprising silica-based particles comprising modification with

US Pat. No. 6,372,806 (a) charges a reaction vessel with a cation exchange resin having at least 40% of the ion exchange capacity in hydrogen form (the reaction vessel has means for separating colloidal silica from the ion exchange resin) ), (B) charging the reaction vessel with an aqueous alkali metal silicate solution having a molar ratio of SiO ₂ to alkali metal oxide ranging from 15: 1 to 1: 1 and a pH of at least 10.0; Stirring the contents of the reaction vessel until the pH of the contents is in the range of 8.5 to 11.0, (d) using an additional amount of the alkali metal silicate to pH the contents of the reaction vessel And (e) a stable colloidal silica having an S-value of 20-50 comprising separating the resulting colloidal silica from the ion exchange resin and removing the colloidal silica from the reaction vessel ( The silica is 700m ² / g (Having a larger surface area).

U.S. Pat. No. 5,176,891 (a) acidifying a dilute solution of alkali metal silicate containing about 0.1 to 6 wt% SiO2 to a pH of ₂ to 10.5 to produce polysilicic acid, followed by (b ) Reacting a water-soluble aluminate with the polysilicic acid (then the polysilicic acid gels, resulting in a product having an alumina / silica molar ratio greater than about 1/100), then (c) the A water-soluble polyaluminosilicate having a surface area of at least about 1,000 m ² / g, including the step of diluting the reaction mixture (after which gelation occurs to an equivalent of SiO ₂ of about 2.0 wt% or less to stabilize the microgel) A method for producing a microgel is disclosed.

It would be advantageous to be able to provide a silica-based sol with improved stability and SiO ₂ content as well as improved dewatering performance. It would also be advantageous to be able to provide an improved process for preparing silica-based sols with improved dewatering performance as well as stability and SiO ₂ content. It would also be advantageous to be able to provide a papermaking process with improved dewatering.

The present invention generally
(a) preparing a cation exchange resin having at least part of the ion exchange capacity of the hydrogen form,
(b) contacting the ion exchange resin with an aqueous alkali metal silicate solution to produce an aqueous slurry;
(c) Stir the aqueous slurry until the pH of the aqueous phase is in the range of 5.0 to 11.5 and / or stir the aqueous slurry to enable particle aggregation or microgel formation corresponding to S values up to 45% And obtain an aqueous phase pH of at least 5.0,
(d) adjusting the pH of the aqueous phase to 9.0 or more using one or more materials comprising at least one aluminum compound; and
(e) The present invention relates to a method for producing an aqueous silica-based sol, wherein the ion exchange resin is separated from the aqueous phase after step (c) or after step (d).

Furthermore, the present invention generally
(a) Prepare a reaction vessel,
(b) in the reaction vessel
(i) a cation exchange resin having at least part of the ion exchange capacity in the hydrogen form, and
(ii) preparing an aqueous slurry by preparing an aqueous alkali metal silicate solution;
(c) Stir the aqueous slurry until the pH of the aqueous phase is in the range of 5.0 to 11.5 and / or stir the slurry to enable particle aggregation or microgel formation corresponding to S values up to 45%. Obtaining an aqueous phase pH of at least 5.0,
(d) adding one or more materials containing at least one aluminum compound to the aqueous phase obtained after step (c) to produce an aqueous phase having a pH of 9.0 or higher;
(e) The present invention relates to a method for producing an aqueous silica-based sol, wherein the ion exchange resin is separated from the aqueous phase after step (c) or after step (d).

Furthermore, the invention relates to a silica-based sol obtainable by these methods. Furthermore, the present invention generally relates to silica-based sols and, in particular, S values in the range of 15-25%, molar ratios Si: Al in the range 20: 1 to 50: 1, 5: 1 to 17: Including silica-based particles having a molar ratio Si: X in the range of up to 1 (where X is an alkali metal), a SiO ₂ content of at least 5% by weight and a specific surface area of at least 300 m ² / g It relates to a sol based on silica.

  Furthermore, the invention relates to the use of the silica-based sols according to the invention, in particular as dehydration and retention aids in papermaking and for water purification.

Furthermore, the present invention generally
(a) preparing an aqueous suspension containing cellulose fibers;
(b) adding to the suspension one or more dehydration and retention aids comprising a silica-based sol of the invention specified herein; and
(c) It relates to a method for producing paper, comprising dehydrating the resulting suspension to obtain a paper sheet or web.

  The present invention provides a silica-based sol suitable for use as a flocculant in water purification and as a dewatering and retention aid in papermaking. The silica-based sols of the present invention exhibit good stability over time, notably high surface area stability and high stability to avoid complete gel formation. This silica-based sol further provides very good dewatering and yield when used in papermaking, in particular improved dewatering. Thereby, the present invention increases the speed of the paper machine and allows the use of low dose additives to produce a corresponding dewatering effect, thereby providing improved papermaking methods and economic benefits. . The silica-based sols of the present invention can be prepared by a method that is simple, rapid, and easy to control and adjust, which makes it possible to utilize simple and inexpensive manufacturing equipment. Thereby, the silica sol of the present invention can be produced by a simplified, improved and more economical method.

  The ion exchange resin used in the process is cationic and has at least part of the ion exchange capacity in the hydrogen form, ie an acid cation exchange resin, preferably a weak acid cation exchange resin. Suitably, the ion exchange resin has at least 40%, preferably at least 50% of the ion exchange capacity of the hydrogen form. Suitable ion exchange resins are marketed by several manufacturers, for example, from Rohm & Haas as Amberlite® IRC84SP. Preferably, the ion exchange resin is charged into a mixing vessel, for example, a reaction vessel equipped with a stirrer. Preferably, the ion exchange resin is regenerated by addition of an acid, such as sulfuric acid, preferably according to the manufacturer's instructions.

Step (b) of the method involves combining the cation exchange resin with an aqueous alkali metal silicate solution. Preferably, this is accomplished by adding an ion exchange resin and an aqueous alkali metal silicate solution to the reaction vessel. Preferably, a reaction vessel containing the regenerated ion exchange resin is charged with an aqueous alkali metal silicate solution, thereby producing an aqueous slurry. Usually, the alkali metal silicate aqueous solution is calculated as an ion exchange resin having 100% of the ion exchange capacity in the hydrogen form, and 0.5 to 50 g per minute and 1 kg of the ion exchange resin, preferably 1 to 35, preferably It is added to a reaction vessel containing an ion exchange resin having at least part of the ion exchange capacity in hydrogen form at a rate in the range of _{2 to} 20 SiO2. The regenerated ion exchange resin is charged into a reaction vessel containing the alkali metal silicate aqueous solution, thereby generating an aqueous slurry.

Examples of suitable alkali metal silicate aqueous solutions or water glasses include conventional materials such as lithium silicate, sodium silicate and potassium silicate, preferably sodium silicate. The molar ratio of silica to alkali metal oxide, such as SiO ₂ to Na ₂ O, K ₂ O or Li ₂ O, or mixtures thereof in this silicate solution ranges from 15: 1 to 1: 1. May be in the range of 4.5: 1 to 1.5: 1, preferably 3.9: 1 to 2.5: 1. The alkali metal silicate aqueous solution used is about 2% to about 35%, preferably about 5% to about 30%, preferably about 15% to about 25% by weight of SiO _2. May have a content. The pH of this aqueous alkali metal silicate solution is usually 11 or higher, typically 12 or higher.

Step (c) of the process involves stirring the aqueous slurry produced in step (b) until the pH of the aqueous phase is in the range of 5.0 to 11.5. Alternatively or additionally, step (c) of the method comprises stirring the aqueous slurry to enable particle aggregation or microgel formation corresponding to an S value of up to 45%, and to obtain an aqueous phase pH of at least 5.0. Including. Stirring is preferably carried out until the pH of the aqueous phase is in the range of 6.0 to 11.0, preferably in the range of 6.5 to 10.0. In one preferred embodiment of the invention, the slurry is stirred until the pH of the aqueous phase is up to 8.0, suitably from 6.0 to 8.0, preferably from 6.5 to 7.5. In another preferred embodiment of the invention, the slurry is stirred until the pH of the aqueous phase is at least 8.0, suitably from 8.0 to 11.0, preferably from 9.0 to 10.0. It is preferred that particle growth occur while stirring the aqueous slurry. The produced silica-based particles usually have a specific surface area of at least 300 m ² / g, preferably at least 700 m ² / g. This specific surface area is suitably up to 1,500 m ² / g, preferably up to 1,000 m ² / g. The slurry is preferably agitated to obtain particle aggregation and microgel formation, usually in the range of 5-45%, suitably 8-35%, preferably 10-25%, most preferably 15-23%. Stirring is allowed to make it possible to correspond to the S value. This stirring is usually performed during a period of time of 5 to 240 minutes, preferably 15 to 120 minutes.

  Step (c) of the method may be performed simultaneously with and / or after step (b). In a preferred embodiment, the aqueous alkali metal silicate solution is added to a reaction vessel containing an ion exchange resin having at least a part of the ion exchange capacity in the hydrogen form with stirring, and after completion of the addition, stirring is performed as described above. Until pH and / or particle agglomeration or microgel formation is obtained. In another preferred embodiment, the aqueous alkali metal silicate solution is added with stirring to a reaction vessel containing an ion exchange resin having at least a part of the ion exchange capacity in the hydrogen form, and the pH and / or particles as described above. Aggregation or microgel formation is obtained.

  Step (d) of the method includes adding one or more materials including at least one aluminum compound to the aqueous phase. The pH of the aqueous phase is suitably adjusted to 9.0 or higher, preferably 10.0 or higher, suitably 9.2 to 11.5, preferably 9.5 to 11.2, most preferably 10.0 to 11.0. This pH is preferably adjusted by adding one or more materials containing at least one aluminum compound, preferably this pH is raised by adding one or more alkaline materials containing at least one aluminum compound. The In a preferred embodiment, an aluminum compound is added. In another preferred embodiment, an alkaline material and an aluminum compound are added. Examples of suitable aluminum compounds include not only alkaline aluminum salts, but also neutral and substantially neutral aluminum salts. Examples of suitable alkaline aluminum salts include aluminates, preferably aqueous aluminate solutions such as sodium aluminate and potassium aluminate, preferably sodium aluminate. An example of a neutral and substantially neutral aluminum salt is aluminum nitrate. Examples of suitable alkaline materials include aqueous alkali metal silicates such as any of those previously identified; aqueous alkali metal hydroxides such as lithium hydroxide, sodium hydroxide and potassium hydroxide, preferably water Sodium oxide; ammonium hydroxide; preferably sodium silicate or sodium hydroxide, preferably sodium silicate. When using two or more materials including an alkaline material and an aluminum compound, these materials can be added in any order, preferably the alkaline material is added first, followed by the aluminum compound. In a preferred embodiment, the aqueous alkali metal silicate solution is added first, followed by the aqueous sodium aluminate solution. In another preferred embodiment, the aqueous alkali metal hydroxide solution is added first, followed by the aqueous sodium aluminate solution. Addition of an aluminum compound gives a silica-based sol treated with aluminate. Suitably, the addition of an aluminum compound results in aluminum modification of the silica-based particles, preferably these particles are surface modified with aluminum. The amount of aluminum compound used can vary within wide limits. Usually the amount of aluminum compound added is from 10: 1 to 100: 1, suitably from 20: 1 to 50: 1, preferably from 25: 1 to 35: 1, most preferably from 25: 1 to 30. Corresponds to a Si: Al molar ratio of up to 1: 1.

  In step (d) of the method, when the pH of the aqueous phase is adjusted using an aqueous alkali metal silicate solution, the alkali metal silicate used in step (b) is used in step (d). The weight ratio of alkali metal silicates can vary within wide limits. Usually, the ratio ranges from 99: 1 to 1: 9, preferably from 19: 1 to 1: 2, preferably from 4: 1 to 1: 1.

  In step (e) of the method, the ion exchange resin is separated from the aqueous phase, for example, by filtration. This can be done after step (c), for example after step (c) but before step (d) or after step (d). It is also possible to separate the ion exchange resin from the aqueous phase during step (d). For example, the ion exchange resin can be separated after adding an alkaline material but before adding an aluminum compound. It is also possible to add a part of an alkaline material, for example an aqueous alkali metal silicate solution, then separate the ion exchange resin from the aqueous phase and subsequently add the remainder of the alkaline material. The ion exchange resin is preferably separated from the aqueous phase after step (d).

The concentration of the aqueous starting material solution used in the process, for example, the alkali metal silicate aqueous solution, alkali metal hydroxide aqueous solution and sodium aluminate aqueous solution is usually at least 3% by weight, preferably at least 5% by weight, Preferably adjusted to obtain a silica-based sol having a SiO ₂ content of at least 6% by weight, most preferably at least 7.5% by weight and suitably up to 20% by weight, preferably up to 15% by weight. Is preferred. Silica-based sols produced by the method of the present invention may have the properties specified below.

The silica-based sol aqueous solutions of the present invention are silica-based particles, ie, silica or SiO ₂ -based particles (these are anions, preferably colloids, ie in the colloidal range of particle size. )including. These particles are suitably modified with aluminum, preferably surface modified with aluminum. The silica-based sols of the present invention are 10: 1 to 100: 1, suitably 20: 1 to 50: 1, preferably 25: 1 to 35: 1, most preferably 25: 1 to 30. May have a Si: Al molar ratio of up to 1: 1.

  The silica-based sols of the present invention may have S values in the range of 10-50%, suitably 12-40%, preferably 15-25%, most preferably 17-24%. This S value is measured and calculated as described by Iler & Dalton, J. Phys. Chem. 60 (1956), 955-957. The S value indicates the degree of agglomeration or microgel formation, and a low S value indicates a high degree of aggregation.

The silica-based particles present in the sol may have a specific surface area of at least 300 m ² / g, suitably at least 700 m ² / g, preferably at least 750 m ² / g. This specific surface area is usually up to 1,000 m ² / g, preferably up to 950 m ² / g. This specific surface area is found in samples that can disturb titrations such as aluminum compounds and boron compounds, as described, for example, by Sears, Analytical Chemistry 28 (1956): 12, 1981-1983 and U.S. Pat.No. 5,176,891. After appropriate removal of the compounds present or adjustments thereto, they are determined by titration with NaOH as described by Sears literature.

  The silica-based sols of the present invention are usually at least 3: 1, suitably at least 4: 1, preferably at least 5: 1, most preferably at least 6: 1 Si: X (where X is an alkali metal) Having a molar ratio of The molar ratio of Si: X (X is an alkali metal) is usually up to 25: 1, suitably up to 20: 1, preferably up to 17: 1, more preferably up to 15: 1, most preferably 10 :. Up to one.

The silica-based sol of the present invention is preferably stable. The sol is at least 300m ² / g, preferably preferred to maintain a specific surface area of at least 700 meters ² / g for at least 3 months of storage or aging of 20 ° C. under conditions which will not stirred in the dark. Suitably, the sol maintains an S value in the range of 10-50%, preferably 12-40% over at least 3 months of storage or aging at 20 ° C. in the dark without stirring.

  The silica-based sols according to the invention are used, for example, as flocculants in the production of pulp and paper, notably as dehydration and retention aids, and for the purification of different types of wastewater and in particular pulp and paper. Suitable for use within the field of water purification, both for the purification of white water from industry. This silica-based sol can be used as a flocculant, notably a dehydration and retention aid, in combination with anionic, amphoteric, nonionic and cationic polymers and organic polymers which can be selected from mixtures thereof. . The use of such polymers as flocculants and dehydration and retention aids is known in the art. These polymers can be derived from natural or synthetic sources, which may be linear, branched or crosslinked. Examples of generally preferred main polymers include anionic, amphoteric and cationic starch; anionic, amphoteric and cationic acrylamide-based polymers (substantially linear, branched and crosslinked anionic and cationic) As well as cationic poly (diallyldimethylammonium chloride), cationic polyethylenimine, cationic polyamine, cationic polyamidoamine and vinylamide based polymers, melamine-formaldehyde resins and Examples include urea-formaldehyde resins. The silica-based sol is preferably used in combination with at least one cationic or amphoteric polymer, preferably a cationic polymer. Cationic starch and cationic polyacrylamide are particularly preferred polymers, which can be used alone, together with each other, or with other polymers, such as other cationic polymers and / or anionic polymers. The molecular weight of the polymer is suitably 1,000,000 or more, preferably 2,000,000 or more. The upper limit is not important. It may be about 50,000,000, usually 30,000,000, preferably about 25,000,000. However, the molecular weight of polymers derived from natural sources may be higher.

  The silica-based sol can also be used in combination with one or more cationic coagulants, with or without the simultaneous use of one or more organic polymers. Examples of suitable cationic coagulants include water soluble organic polymer coagulants and inorganic coagulants. This cationic coagulant can be used alone or together, ie the polymer coagulant can be used in combination with an inorganic coagulant.

  Examples of suitable water-soluble organic polymer cationic coagulants include cationic polyamines, polyamidoamines, polyethyleneimines, dicyandiamide condensation polymers and water-soluble ethylenically unsaturated monomers or monomer blends (this includes 50 to 100 mole percent cations Polymer produced from 0 to 50 mol% of other monomers). The amount of cationic monomer is usually at least 80 mol%, preferably 100%. Examples of suitable ethylenically unsaturated cationic monomers include dialkylaminoalkyl acrylate, dialkylaminoalkyl methacrylate, dialkylaminoalkyl acrylamide and dialkylaminoalkyl methacrylamide, and diallyldialkylammonium chloride, preferably in quaternized form, For example, diallyldimethylammonium chloride (DADMAC), preferably homopolymers and copolymers of DADMAC. The organic polymeric cationic coagulant usually has a molecular weight in the range of 1,000 to 700,000, preferably 10,000 to 500,000. Examples of suitable inorganic coagulants include aluminum compounds such as alum and polyaluminum compounds such as polyaluminum chloride, polyaluminum sulfate, polyaluminum silicate sulfate and mixtures thereof.

  The components of the dehydrating and retention aid of the present invention can be added to the stock in any order in the usual manner. When using a dehydration and retention aid comprising a silica-based sol and an organic polymer, the organic polymer is added prior to the addition of the silica-based sol, even if the reverse order of addition may be used. It is preferable to add to the stock. More preferably, the organic polymer is added before the shearing stage (which is selected from pumping, mixing, washing, etc.) and the silica-based sol is added after the shearing stage. If a cationic coagulant is used, it is preferably added to the cellulosic suspension before the addition of the silica-based sol and preferably before the addition of one or more organic polymers.

Each component of the dehydration and retention aid of the present invention varies within wide limits depending on, among other things, the type and number of each component, the type of furnish, the content of filler, the type of filler, the point of addition, etc. It is added to the stock to be dehydrated in the amount obtained. In general, these components are added in amounts that provide better dehydration and yield than would be obtained without the addition of each component. Sol dry furnish based on the silica, i.e., dry cellulosic fibers and optional heaven fee calculated as SiO ₂ as a reference, usually at least 0.001% by weight, often added in an amount of at least 0.005 wt%, The upper limit is usually 1.0% by weight, preferably 0.5% by weight. The organic polymer is usually added in an amount of at least 0.001% by weight, often at least 0.005% by weight, based on the dry furnish, and the upper limit is usually 3% by weight, preferably 1.5% by weight. If a cationic polymer coagulant is used, it can be added in an amount of at least 0.05% based on the dry furnish. Suitably the amount is in the range of 0.07 to 0.5%, preferably in the range of 0.1 to 0.35%. When an aluminum compound is used as the inorganic coagulant, the total amount added is usually at least 0.05%, calculated as Al ₂ O _{3 based on the} dry furnish. Suitably the amount is in the range of 0.1-3.0%, preferably in the range of 0.5-2.0%.

  Additional additives that are usual in papermaking can of course be used in combination with the additives of the present invention, for example, dry strength enhancers, wet strength enhancers, fluorescent whitening agents, dyes, rosin-based sizing agents And sizing agents such as cellulose reactive sizing agents such as alkyl ketene dimers and alkenyl ketene dimers and ketene multimers, alkyl succinic anhydrides and alkenyl succinic anhydrides. The cellulosic suspensions or stocks are also of the usual types of inorganic fillers such as kaolin, china clay, titanium dioxide, gypsum, talc and natural and synthetic calcium carbonates such as chalk, ground marble and precipitated calcium carbonate Can be included.

  The method of the present invention is used for paper manufacture. The term “paper” as used herein, of course, includes not only paper and its products, but also other products such as cellulose sheets or webs, such as paperboard and paperboard, and these products. The method can be used to make paper from different types of suspensions of cellulose-containing fibers, which suspension is suitably at least 25% by weight, preferably at least 50% by weight, based on dry matter Should contain good fiber. The suspension is from both hardwood and coniferous chemical pulps such as sulfate pulp, sulfite pulp and organic solvent pulp, mechanical pulp such as thermomechanical pulp, chemothermomechanical pulp, refiner pulp and groundwood pulp. It can be based on fibers, and on the basis of recycled fibers, and mixtures thereof, if necessary, from deinked pulp. The pH of the suspension or stock may be in the range of about 3 to about 10. The pH is suitably at least 3.5, preferably in the range of 4-9.

  The invention will be further described in the following examples, which are not intended to limit the invention. Parts and percentages relate to parts by weight and percentages by weight, respectively, unless otherwise specified.

  The following equipment and starting materials were used in the examples.

(a) a reactor equipped with a stirrer,
(b) Ion exchange resin Amberlite® IRC84SP (available from Rohm & Haas) (which was regenerated with sulfuric acid according to the manufacturer's instructions),
(c) an aqueous sodium silicate solution having a SiO ₂ content of about 21 wt% and a molar ratio of SiO ₂ to Na ₂ O of 3.32;
(d) a sodium aluminate aqueous solution containing 2.44 wt% Al ₂ O ₃ , and
(e) A sodium hydroxide aqueous solution having a concentration of 5 moles per kilogram.
[Example 1]
This example illustrates the preparation of a silica-based sol of the present invention. Regenerated ion exchange resin (471 g) and water (1,252 g) were charged to the reactor. The resulting slurry was stirred vigorously and heated to a temperature of 30 ° C. Aqueous sodium silicate solution (298 g) was then added to the slurry at a rate of 5 g / min. After the addition of sodium silicate, the pH of the slurry was about 7.3. The slurry was then stirred for an additional 44 minutes after which the pH of the aqueous phase was 6.9. Thereafter, additional aqueous sodium silicate solution (487 g) was added to the slurry at a rate of 5 g / min, after which the pH of the aqueous phase was 10.4. The resulting aqueous phase was separated from the ion exchange resin. Aqueous sodium aluminate (52 g) was added to the sol (527.4 g) under vigorous stirring over a period of 10 minutes.

The resulting silica-based sol had the following properties: SiO ₂ content = 7.7 wt%; molar ratio Si: Na = 7.5; molar ratio Si: Al = 26.2; pH = 10.7; specific surface area = 790 m ² / g; and S value = 18%.
[Example 2]

  This example illustrates the preparation of another silica-based sol of the present invention. An ion exchange resin (1,165 g) (which was regenerated to about 40% of the ion exchange capacity) and water (686 g) were charged to the reactor. The resulting aqueous slurry was stirred vigorously. A sodium silicate aqueous solution (989 g) was then added to the slurry over a period of 10 minutes. After the addition of sodium silicate, the pH of the aqueous slurry was about 10.7. The slurry was then stirred for 22 minutes after which the resulting pH of the aqueous slurry was 9.8. Thereafter, additional aqueous sodium silicate solution (128 g) was added to the slurry in 1 minute, after which the pH of the aqueous slurry was 10.3. The aqueous phase was separated from the ion exchange resin. Aqueous sodium aluminate (57 g) was added to the aqueous phase (463 g) at a rate of 5.7 g / min with vigorous stirring.

The resulting silica-based sol had the following properties: SiO ₂ content = 10.3 wt%; molar ratio Si: Na = 4.9; molar ratio Si: Al = 33.6; pH = 11.0; specific surface area = 1,000 m ² / g; and S value = 23%.
[Example 3]

  This example illustrates the preparation of yet another silica-based sol of the present invention. Regenerated ion exchange resin (600 g) and water (1,600 g) were charged to the reactor. The resulting aqueous aqueous slurry was stirred vigorously and heated to a temperature of 30 ° C. An aqueous sodium silicate solution (764 g) was then added to the slurry at a rate of 6.8 g / min. After the addition of sodium silicate, the pH of the aqueous slurry was about 8, after which the ion exchange resin was separated from the aqueous phase. Aqueous sodium hydroxide (30 g) was added to the aqueous phase at a rate of 10 g / min, after which the pH of the aqueous phase was 10. An aqueous sodium aluminate solution (83 g) was then added to the aqueous phase (776 g) under vigorous stirring over a period of 10 minutes.

The resulting silica-based sol had the following properties: SiO ₂ content = 6.1 wt%; molar ratio Si: Na = 5.9; molar ratio Si: Al = 20.3; pH = 10.9; specific surface area = 930 m ² / g; and S value = 22%.
[Example 4]

  This example illustrates the preparation of another silica-based sol of the present invention. An ion exchange resin (1,785 g) (which was regenerated to about 40% of the ion exchange capacity) and water (920 g) were charged to the reactor. The resulting aqueous slurry was stirred vigorously. A sodium silicate aqueous solution (1,390 g) was then added to the slurry over a period of 10 minutes. After the addition of sodium silicate, the pH of the aqueous slurry was about 10.4. The slurry was then stirred for 25 minutes after which the pH of the aqueous slurry was 9.2. The ion exchange resin was separated from the aqueous phase. Aqueous sodium hydroxide (15.5 g) was added to the aqueous phase over a period of about 2 minutes, after which the pH of the aqueous phase was 10. Aqueous sodium aluminate (56.7 g) was added to the aqueous phase (483 g) at a rate of 5.7 g / min with vigorous stirring.

The resulting silica-based sol had the following properties: SiO ₂ content = 9.8 wt%; molar ratio Si: Na = 6.1; molar ratio Si: Al = 30.2; pH = 10.8; specific surface area = 940 m ² / g; and S value = 22%.
[Example 5]

  The following silica-based sols, Reference Examples 1 to 4, were prepared for comparative purposes.

  Reference Example 1 is a silica-based sol prepared according to the disclosure of Example 4 of US Pat. Nos. 6,372,089 and 6,372,806.

Reference Example 2 is a silica-based sol prepared according to the disclosure of US Pat. No. 5,368,833, which has an S value of about 25%, a Si: Al molar ratio of about 19 and about 900 m ² / g Contains silica particles having a specific surface area of SiO ₂ (these were surface modified with aluminum).

Reference Example 3 is a silica-based sol prepared according to the disclosure of US Pat. No. 5,603,805, which contains silica particles having an S value of about 34% and a specific surface area of about 700 m ² / g. It was out.

Reference Example 4 is a silica-based sol prepared according to the disclosure of US Pat. No. 5,368,833, which has a S value of 20%, a Si: Al molar ratio of about 18 and about 820 m ² / g. Silica particles having a specific surface area of SiO ₂ (these were surface modified with aluminum) were included.
[Example 6]

  In the tests below, the silica-based sol dehydration performance of Examples 1 and 2 ("Example 1" and "Example 2", respectively) is compared to the silica-based sol dehydration performance of Example 5. Tested. Dynamic Dehydration Analyzer (DDA) available for dewatering performance from Acrivi, Sweden (this is a set volume through the wire when the plug is removed and a vacuum is applied to the side of the wire opposite to the side where the stock is present The time for dehydrating the paper stock is measured.

The paper stock used was based on a regular premium paper furnish consisting of 60% bleached sulfuric acid hippo and 40% bleached sulfuric acid pine. 30% ground calcium carbonate was added to the paper stock as a filler, and 0.3 g / l Na ₂ SO ₄ .10H ₂ O was added to increase the conductivity. The stock pH was 8.1, the conductivity was 1.5 mS / cm, and the consistency was 0.5%. In these tests, a silica-based sol was tested with a cationic starch having a degree of substitution of about 0.042. This starch was calculated as the dry starch of the dry furnish and added in an amount of 8 kg / ton.

This stock was stirred in a jar with a baffle plate at a speed of 1,500 rpm during the test, and chemicals were added to the stock as follows.
i) Add cationic starch, then stir for 30 seconds,
ii) Add silica-based sol, followed by stirring for 15 seconds,
iii) Dehydrate the stock while automatically recording the dehydration time.

Table 1 shows the results obtained when using various doses of silica based sol (kg / ton calculated as SiO ₂ based on dry furnish).

[実施例７]

[Example 7]

The dehydration performance of the silica-based sol of Example 1 was further evaluated. The procedure of Example 6 was followed except that cationic polyacrylamide (“PAM”) was used in place of the cationic starch. In addition, the stock was agitated in a jar with baffles during the test at a speed of 1,500 rpm, and chemicals were added to the stock as follows.
i) Add cationic polyacrylamide, followed by stirring for 20 seconds,
ii) Add silica-based sol, followed by stirring for 10 seconds,
iii) Dehydrate the stock while automatically recording the dehydration time.

Table 2 shows different doses of cationic polyacrylamide (calculated as dry starch of dry furnish, kg / ton) and silica-based sol (calculated as SiO ₂ based on dry furnish, The results obtained when using (kg / ton) are shown.

[実施例８]

[Example 8]

The dehydration performance of the silica-based sols of Examples 3 and 4 was tested according to the procedure of Example 6. Table 3 shows the results obtained when using various doses of silica based sol (kg / ton calculated as SiO ₂ based on dry furnish).

[実施例８]

[Example 8]

The dehydration performance of the silica-based sols of Examples 3 and 4 was tested according to the procedure of Example 7. Table 4 shows the results (calculated as SiO _2, kg / ton, based on dry furnish) was obtained when using a sol based on silica various doses.

Claims (31)

(a) preparing a cation exchange resin having at least part of the ion exchange capacity of the hydrogen form,
(b) contacting the ion exchange resin with an aqueous alkali metal silicate solution to produce an aqueous slurry;
(c) stirring the aqueous slurry until the pH of the aqueous phase is in the range of 5.0 to 11.5, or stirring the aqueous slurry to enable particle aggregation or microgel formation corresponding to an S value of up to 45%; Obtain an aqueous phase pH of at least 5.0;
(d) adjusting the pH of the aqueous phase to 9.0 or more using one or more materials comprising at least one aluminum compound; and
(e) A method for producing an aqueous silica-based sol, wherein the ion exchange resin is separated from the aqueous phase after step (c) or after step (d). (a) Prepare a reaction vessel,
(b) in the reaction vessel
(i) a cation exchange resin having at least part of the ion exchange capacity in the hydrogen form, and
(ii) preparing an aqueous slurry by preparing an aqueous alkali metal silicate solution;
(c) stirring the aqueous slurry until the pH of the aqueous phase is in the range from 5.0 to 11.5, or stirring the slurry to enable particle aggregation or microgel formation corresponding to an S value of up to 45%, Obtain an aqueous phase pH of 5.0,
(d) adding one or more materials containing at least one aluminum compound to the aqueous phase obtained after step (c) to produce an aqueous phase having a pH of 9.0 or higher;
(e) A method for producing an aqueous silica-based sol, wherein the ion exchange resin is separated from the aqueous phase after step (c) or after step (d).   3. A process according to any one of claims 1-2, further comprising (f) obtaining an aqueous silica-based sol having an S value of 10-50%.   The process according to any one of claims 1 to 3, wherein the ion exchange resin is separated from the aqueous phase after step (c) and before step (d).   The method according to any one of claims 1 to 4, wherein the ion exchange resin is separated from the aqueous phase after step (d).   6. The method of any one of claims 1-5, wherein in step (d), the one or more materials comprise an alkaline material.   The method of claim 5, wherein the alkaline material comprises an aqueous alkali metal silicate solution.   The method of claim 5, wherein the alkaline material comprises an aqueous alkali metal hydroxide solution.   9. The process according to claim 1, wherein in step (c) the aqueous slurry is agitated to enable particle aggregation or microgel formation corresponding to S values of up to 45% and to obtain a pH of the aqueous phase of at least 5.0. The method described in the paragraph.   The process according to any one of claims 1 to 9, wherein in step (c) the aqueous slurry is stirred until the pH of the aqueous phase is in the range of 5.0 to 11.5.   The method according to any one of claims 1 to 10, wherein in step (c), the aqueous slurry is stirred until the pH of the aqueous phase is in the range of 6.0 to 8.0.   12. A process according to any one of the preceding claims, wherein in step (c) the aqueous slurry is stirred until the pH of the aqueous phase is in the range of 6.5 to 7.5.   The method according to any one of claims 1 to 10, wherein in step (c), the aqueous slurry is stirred until the pH of the aqueous phase is in the range of 9.0 to 10.0.   14. A process according to any one of the preceding claims, wherein in step (c) the slurry is agitated to enable particle aggregation or microgel formation corresponding to S values in the range of 10-25%.   The method according to any one of claims 1 to 14, wherein in step (d), the aluminum compound is sodium aluminate.   16. The method of any one of claims 1-15, wherein in step (d), the pH of the aqueous phase is adjusted to be in the range of about 9.5 to about 11.2.   17. The method according to any one of claims 1 to 16, wherein in step (d), the aqueous phase is adjusted by first adding an aqueous sodium silicate solution followed by an aqueous sodium aluminate solution.   In step (d), the pH of the aqueous phase is first adjusted by adding an aqueous alkali metal silicate solution, then the ion exchange resin is separated from the aqueous phase, and then the aqueous aluminum compound solution is obtained. 18. A process according to any one of claims 1 to 17 which is added to the phase.   The process according to any one of claims 1 to 16, wherein in step (d), the aqueous phase is adjusted by first adding an aqueous sodium hydroxide solution followed by an aqueous sodium aluminate solution. S value in the range of 15-25%, molar ratio Si: Al in the range from 20: 1 to 50: 1, molar ratio Si: X in the range from 5: 1 to 17: 1, where X is an alkali metal A silica-based sol comprising silica-based particles having a SiO ₂ content of at least 5% by weight and a specific surface area of at least 300 m ² / g.   21. The silica-based sol according to claim 20 or any one of claims 1 to 19, wherein the silica-based sol has a molar ratio Si: X ranging from 6: 1 to 10: 1. the method of.   22. The silica-based sol according to claim 20 or 21, or the method according to any one of claims 1 to 19 and 21, wherein the silica-based sol has an S value in the range of 17-24%. . 23. The silica-based sol according to any one of claims 20 to 22, or wherein the silica-based sol comprises silica-based particles having a specific surface area of 700 to 950 m < ² > / g. The method according to any one of 1 to 19 and 21 to 22. Sol sol based on the silica has a SiO ₂ content ranging from 6% to 15% by weight, based on silica according to any one of claims 20 23, or from claim 1 19 24. The method according to any one of 21 to 23.   25. A sol based on silica obtained by the method of any one of claims 1 to 24. (i) preparing an aqueous suspension containing cellulose fibers;
(ii) adding one or more dehydration and retention aids including a silica-based sol to the suspension; and
(iii) A method for producing paper, comprising dehydrating the resulting suspension to obtain a paper sheet or web,
20. A method for producing paper, characterized in that the silica-based sol is obtained by the method according to any one of claims 1-19. (i) preparing an aqueous suspension containing cellulose fibers;
(ii) adding one or more dehydration and retention aids including a silica-based sol to the suspension; and
(iii) A method for producing paper, comprising dehydrating the resulting suspension to obtain a paper sheet or web,
25. A method for producing paper, characterized in that the sol is a silica-based sol according to any one of claims 20 to 24.   28. A method according to claim 26 or 27, wherein the dehydration and retention aid comprises a cationic starch.   29. A method according to any one of claims 26 to 28, wherein the dehydration and retention aid comprises a cationic synthetic polymer.   30. A method according to any one of claims 26 to 29, wherein the dehydration and retention aid comprises an anionic polymer.   31. A method according to any one of claims 26 to 30, wherein the method comprises adding a cationic coagulant to the suspension.